1. Technical Field
The method and apparatus of the present invention relate generally to earth sheltered, multi-level structures. More specifically, the present invention relates to a method and apparatus for constructing the exterior frame of a multi-level earth-sheltered structure. As is well known in the art, subterranean structures are subject to significant lateral pressure. The novel design of the structure's frame minimizes the effect of this lateral pressure exerted by the earth against the sides of the structure. The minimization of lateral forces simplifies the design and cost of the structure. This allows a multi-level structure, heretofore too expensive, to be created.
Currently, most earth-sheltered structures utilize substantially vertical exterior framing similar to above ground structures. As is well known in the art, the earth exerts substantial lateral pressure below the surface acting against the sides of a structure. When vertical walls are used, this exterior framing is perpendicular to the lateral pressure. Consequently, the force acting on the external structure is maximized. As a result, the structure must be designed so as to withstand this horizontal pressure. As is also understood in the art, these forces vary linearly with depth. Therefore, a correspondingly more substantial structure is required as the depth, i.e. number of subterranean floors is increased. Clearly, as the substantiality of the structure increases, so to does its cost.
Due primarily to cost considerations, the current practice for construction of earth-sheltered structures, is to utilize a single level below ground. If a multi-level structure is desired, this means that at least one level will be "above ground." Clearly, this minimizes the benefits of an earth-sheltered structure.
Implementation of the support structure of the present invention allows multiple subterranean levels to be constructed, maximizing the benefits associated with earth sheltered construction. Use of the techniques taught by the present invention are applicable to both residential dwellings as well as commercial structures.
2. Description of the Prior Art
As mentioned, the most common earth-sheltered structure design implements exterior framing having a generally vertical orientation. Many examples of this exist including the homes illustrated in Homes in the Earth and Earth Sheltered Residential Design Manual. One of the primary concerns in the design of the structure is the earth load on the external walls. As taught in the prior art, this results in a need for shear walls to help resist the lateral forces exerted by such earth loads.
Clearly, there would be many different ways to accommodate this excessive side load. For example, the side wall could be of a sufficient thickness in order to withstand such pressures. Alternatively, materials for construction could be chosen having sufficient strength to withstand these side loads. Still further, bracing or other auxiliary support structures could be used to lend additional support to otherwise conventional framing. Inherent in such construction alternatives is the additional cost which would be associated therewith. Such costs would be not only in additional materials, but also in the labor to install them.
An alternative is to "neutralize" to some degree these lateral forces. This is the novel technique utilized by the present invention which results in a great cost savings both in terms of materials and in construction labor allowing multiple subterranean levels to be constructed.
As will be explained in more detail below, the technique taught by the present invention divides the lateral force present into both horizontal and vertical components thereby decreasing the amount of horizontal pressure which must be accommodated by the wall.
Consequently, there is a great need for a framing structure which permits the cost effective construction of multi-level earth-sheltered structures.
Therefore, it is a primary objective of the present invention to provide a framing apparatus and method of construction for multi-level, earth-sheltered structure wherein sufficient structural support therefor may be obtained without the need for heavy duty internal reinforcing structure.
A further objective of the present invention is to provide a support frame wherein the external wall thereof is slanted at an angle to the subterranean lateral forces thereby dividing the horizontal component of the load factor into a horizontal and vertical component and thereby decreasing the amount of horizontal pressure which must be accommodated by the wall.
It is a further objective of the present invention to provide an "interior frame" support structure wherein all framing members are contained within the exterior wall.
It is a further objective of the present invention to provide an "exterior frame" structure wherein a portion of the supporting structure is located external to the exterior wall.
It is a further objective of the present invention to provide a framing structure wherein safety and convenience are enhanced by having a rear egress.
A further objective is to provide a framing structure wherein an earth covered roof may be supported.
A still further objective is to provide a framing structure wherein a conventional, above earth roof may be supported.
A still further objective of the present invention is to provide a framing structure, portions of which may be preformed and shipped to the construction site for assembly, thereby eliminating the need for on-site assembly of each component of the structure.
It is a further objective of the present invention to provide a framing structure which may be used for a single level structure as well as for multi-level structures.
It is a further objective of the present invention to provide a framing structure adapted to allow air flow to circulate around the structure between the exterior and interior walls creating a "thermal envelope" promoting heating and cooling efficiencies.
It is a further objective of the present invention to provide a framing structure the trusses of which may be constructed from a variety of materials such as wood, steel, aluminum, and the like.
It is a further objective to provide a framing structure wherein the interior may be designed as desired.
It is a final objective to provide a framing structure as described above which may be used for both commercial and residential structures.